Thermal relay



Ocf. 28 1924. 1,513,210

H. F. BANAN THERMAL RELAY Filed June 9, 1920 2; 79 14" HA l 1 2a i a I Z23 21 WITNESSES: Q INVENTOR I g )jvfdaafjfiazzmz BY 1 b ATTORNEY sotion.

Patented Oct. 28, 1924.

UNITED STATES PATENT .oFF ca.

HORACE F. BANAN, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A- CORPORATION OF PENNSYLVANIA.

THERMAL RELAY.

Application filed. June 9,

To all whom it may concern:

Be it known that I, HORACE F. BANAN, a citizen of the United States, anda resident of Pittsburgh, in the county of Allegheny 6 and State ofPennsylvania, have invented a new and useful Improvement in ThermalRelays, of which the following is a specification.

I My invention relates to thermal relays 1 and particularl to bimetallicrelays.v

One object o my invention is to provide a relay havin athermal-responsive device that inherent y shall have such heatingcharacteristics as to ensure effective operation when connected incircuit with a device to be protected, without the use of aux: iliaryheating devices.

Another object of my invention is to provide a bimetallic member that.inherently shall have high electrical resistance.

Another ObJGCt of my invention is to r0 v vide a relay of thecartridgetype that sliall have means whereby the thermal elements andcontact members thereof may .be mount-.

ed as a unit on one ferrule of the cartridge;

A further object of my .invention is to provide a relay, of the above.indicated character, that shall be simple and inexpensive to constructand effectivein its opera- Heretofore, when thermal relays were used forthe protection of electrical apparatus, it was found desirable,especially when the device to be protected consumed a relatively smallvalue of current, to provide a heating element for thethermal-responsive member. This was found necessary by rea son of. thefact that insufficient heating was obtained when the thermal-responsivedevice was made of such mechanicalstructure' as to secure effectiveoperation. In view of the above, I provide a bimetallic member of therequired mechanical strength to obtain effective operation and 4 I slitthe same alternately from opposite ends thereof to constitute anelectrical conductor having relatively high-resistance. 'It will be seenthat,v with this arrangement, sufiicient heat may be generated in a rela0 tively large bimetallic'membenby a rela-,- tively small currenttraversing the same,to cause effective operation thereof, I furthermount the bimetallic element and the contact'members, as a unit, on oneferrule of a 1920; Serial No. 387,579."

device of the cartrid e type, in order to ensure, at all times, e ectivealinement between' the contact members and consequent accuracy ofoperation. Figure 1 of the accompanying drawings 1s a. View of thebimetallic element embodying my invention Fig. 2 is a view of theelefment'shown 1n',F g. 1 having bracing members at the ends thereof. Y

Fig. 3 is a view, partially in elevation and partially in section, of athermal relay embodying my invention, and Fig. 4 is -a diagramillustrating the use of my; invention for the. protection of anelectrical translating device a 0 A motor 1 or other electricaltranslating device to be' protected, isprovided with current from acircuit 2 through an. interrupter 3. The interrupter 3 is provided witha low-voltage holding coil 4 and a spring 5 for actuating the same whenthe coil 4 is de-energiz'ed. The circuit 'offthe coil 4 is controlled bya thermal relay '6 Ivhich is connected in circuit with-the motor I Thethermal relay6,-as shown in Fig. 3,. comprises a cylindrical casing 7,two end ferrules Sand. 9 and a unitary thermal-re-.

in'g block 11- to which-is secured a bimetallic- .member 12 and an arm13 upon the outer end. of which is. mounted a contact member 14, Acontact member 15 is mounted on the I bimetallic member 12 but isinsulated therefrom and is adapted to engage-the contactmember 14.The'block ll'lS securedto the ferrule 8 byrivets- 16.

.Th: bimetallic. member 12 comprises two strips ofm'eta-l'l? and'l8having different 'temperature' coefficients and effectively sew curedtogetherin face-to-facerelatiomj slits 19, 20 and 21 are cut inthemember 12 from theresp'ective'ends thereof in such'mannerasto-greatlyxincrease the res stance to. the flow of current therethrough.That is, with the bimetallic member slit as shown. in. Figs,

,1 and 2, the resistance to the-flow of current from the point. 22- tothe"p0i nt 23 is substantially sixteen 'times as great as the iresistance to the flow'of current from one end ,to the other oftheoriginal strip. The

point-22 of the strip is electrically connected b1}: ordinarycartridge-fuse clips. However,

spacing of the clips is such as to preclude the use of a device of thistype in place of a fuse of the same rating.

Two insulating members and 26 are clamped to the outer end of thebimetallic element 12 for the purpose of so strengthening the same as topreclude uneven expansion of the various parts of the element and alsofor the purpose of insulating the contact member 15 from the strip 12.The contact member 14 is connected, through the supporting member 13 anda conductor 27, to a terminal post 28 which, inturn, is connected,through the coil 4, to conductor 29 of the circuit 2. It will beunderstood that the relay 6 is placed in series with conductor 30 of thecircuit 2 in order that the coil 4 may be connected across the circuit.

Since the bimetallic element 12 is disposed in the casing 7 and, sincethe resistance to the flow of current through the element 12 isrelatively high, it will-readily be seen that the device may be adjustedto cause disengagement of the contact members 14 and 15 when apredetermined value of current has traversed the motor 1 for apredetermined interval of time.

The heating characteristics of the device 6 may be such as to conformexactly to that of the motor 1 or they may be such that the timeinterval is sufiicient to secure adequate protection to the motor 1.

With my device, adequate protection will be obtained, irrespective ofthe current traversing the motor 1. That is, if the motor 1 consumesonly a fraction of an ampere, sufficient'heating will obtain in theelement 12 to cause the same to operate efiectively to deenergize thecoil 4 which permits the s ring 5 to open the interrupter and thusdlsconnect the motor 1 from the circuit. The coil 4, being a low-voltagecoil, will, of course, also permit the interrupter 3 to open when thevoltage across the circuit 2 falls below a predetermined value.

Since the unit 10, comprising the bimetallic element 12 and the contactmembers 14 and 15, is mounted on one ferrule of the de- 'vice, it willbeunderstood that the necessity for accurate alinement of the ferrules 8and 9 is obviated and thus a more accurate device is obtalned with lessexpense.

My invention is not limited to the specific structure illustrated as itmay be-variously modified without departing from the spirit and scope ofthe same, as set forth in the appended claims.

,I claim as my invention:

1. An article of manufacture comprisin a bimetallic stri having slitstherein extending alternate y from opposite ends.

2. An article of manufacture comprising a bimetallic strip having suchslits therein,

extending. from the respective ends thereof, that the resistance of thestrip is relatively arge.

3. An article of manufacture comprising two strips of material ofdifferent coeflicients of'expansion positively secured together inface-to-fa'ce relation and having slits there- 'in extending fromopposite ends thereof.

so formed to cause them to move together when heated, and a contactmember on said means.

7. A thermal relay comprising a bimetallic strip having slits extendingsuch distances, alternately from the respective ends thereof, as toincrease the electrical resistance of the strip and means for securingthe separated portions of each end of the strip together. a

8. A thermal relay comprising a bimetallic strip having slits thereinextending from opposite ends thereof and insulating means adjacent theends thereof for securing the separated portions of the strip togetherto cause the torques of the several portions to be cumulativelyeffective.

9. A thermal relay comprising a bimetallic strip having slits thereinextending from one end thereof, an insulating clamp for one end of thestrip to cause the several portions to move together, means forsupporting one end of the strip, and a contact member supported on andcontrolled by the free end of the strip. I

10. A thermal relay comprising a cylindrical casing, two end ferrulestherefor, and a thermal-responsive device supported as a unit within thecasing on one ferrule and electrically connected between both ferrules.

11. A thermal relay comprising a cylindrical casing, two end ferrulestherefor, a bi- III Ill

metallic element supported on one ferrule only and means forelectrically connecting the same to both ferrules.

12. A thermal relay comprising a cylindrical casing, two end ferrulestherefor, a bimetallic element supported on one ferrule only and meansfor electrically connecting the element to the other ferrule.

13. A thermal relay comprising a cylindrical casing, two end ferrulestherefor, a bimetallic element supported on one ferrule only and so slitfrom the opposite ends thereof as to constitute a conductor ofrelatively high resistance, means for connecting one end of theconductor thus constituted to the supporting ferrule and the other endto the other ferrule.

14. A thermal relay omprising a cylindrical casing, two end ferrulestherefor, an insulating member, a bimetallic member secured to theinsulating member, a stationary contact member mounted on the insulatingmember, a movable contact member mounted on the bimetallic member andmeans for mounting the insulating member on one ferrule only. 1

In testimony whereof, I have hereunto subscribed my name this 4th day ofJune, 1920.

HORACE F. BANAN.

